Methods and apparatus of managing a power amplifier

ABSTRACT

In the present technique for power management of a power amplifier, an amplifier bank from a plurality of amplifier banks in a power amplifier that has been switched off for a longest period of time is assessed ( 826 ) to provide a lowest amplifier bank. With this lowest amplifier bank, an up-threshold that is associated to the lowest amplifier bank is assessed ( 828 ), followed by another assessment ( 820 ) of a current power output of the power amplifier. It is next determined ( 830 ) whether the current power output corresponds at least in a predetermined way to the up-threshold, and if so, the lowest amplifier bank is accordingly switched on ( 832 ).

REFERENCE TO RELATED APPLICATIONS

This application is related to a co-pending application entitled“METHODS AND APPARATUS OF MANAGING A POWER AMPLIFIER,” filed on evendate herewith, assigned to the assignee of the present application, andhereby incorporated by reference.

TECHNICAL FIELD

This invention relates generally to methods and an apparatus of managinga power amplifier.

BACKGROUND

It is well-known that cellular base station power amplifiers are mostefficient when operating at their rated power. These power amplifiersare generally sized for the maximum power required at a cell site'sbusiest hour. In order to conserve power, components are typicallyincluded to place unneeded overhead resources to sleep in the poweramplifier at the device-level architecture. These components aregenerally complementary to other planned efficiency improvements.Because most of these prior art components are not backward compatiblewith legacy equipment, they cannot offer energy savings until multiplemodules are plugged into the frame.

One prior method proposes a sleep mode architecture that placesamplifier modules in and out of service. This architecture, however, isnot self-contained and requires the assistance of an externalcontroller. As a result, granularity is not maximized. This proposedsleep mode architecture typically requires a great deal of coordinationbetween the power amplifiers and a higher level controller to manage theswitching in and out of parallel amplifier modules. Thus, it is not anefficient solution to conserve power.

BRIEF DESCRIPTION OF THE DRAWINGS

The above needs are at least partially met through provision of methodsand an apparatus of managing a power amplifier described in thefollowing detailed description, particularly when studied in conjunctionwith the drawings, wherein:

FIG. 1 comprises an illustration of an exemplary communications systemin which various embodiments may be implemented;

FIG. 2 comprises an illustration of an apparatus in which variousembodiments may be implemented;

FIG. 3 comprises a flow chart of a power management process according tovarious embodiments;

FIG. 4 comprises a flow chart of a switch process shown in FIG. 3according to various embodiments;

FIG. 5 comprises a flow chart of a power management process implementedwith static predefined thresholds of the power amplifier according tovarious embodiments;

FIG. 6 comprises a flow chart of a switch-on process from FIG. 5according to various embodiments;

FIG. 7 comprises a flow chart of a switch-off process from FIG. 5according to various embodiments;

FIG. 8 comprises a flow chart of a power management process implementedwith dynamic predefined thresholds of the amplifier banks according tovarious embodiments;

FIG. 9 comprises a flow chart of a min/max monitored power updateprocess from FIG. 8 according to various embodiments;

FIG. 10 comprises a flow chart of a setup timer expiration processaccording to various embodiments;

FIG. 11 comprises a flow chart of a count timer expiration processaccording to various embodiments;

FIG. 12 comprises a flow chart of a rotation timer expiration processaccording to various embodiments; and

FIG. 13 comprises a flow chart of a rotate banks process according tovarious embodiments.

Skilled artisans will appreciate that elements in the figures areillustrated for simplicity and clarity and have not necessarily beendrawn to scale. For example, the dimensions of some of the elements inthe figures may be exaggerated relative to other elements to helpimprove understanding of various embodiments of the present invention.Also, common and well-understood elements that are useful or necessaryin a commercially feasible embodiment are often not depicted in order tofacilitate a less obstructed view of these various embodiments of thepresent invention.

DETAILED DESCRIPTION

Generally speaking, pursuant to these various embodiments, an amplifierbank from a plurality of amplifier banks in a power amplifier that hasbeen switched off for a longest period of time is assessed to provide alowest amplifier bank. With this lowest amplifier bank, an up-thresholdthat is associated with the lowest amplifier bank is assessed, followedby another assessment of a current power output of the power amplifier.It is next determined whether the current power output corresponds atleast in a predetermined way to the up-threshold, and if so, the lowestamplifier bank is accordingly switched on.

In an embodiment, prior to the assessment of the lowest amplifier bank,a current power output of the power amplifier is assessed, and aprevious power output is set to the current power output, followed bywaiting for a predefined period of time to repeat the method. Accordingto one embodiment, the previous power output and the current poweroutput of the power amplifier are assessed to determine whether theycorrespond at least in a predetermined way, and if not, an amplifierbank that has been switched on for a longest period of time is assessedto provide a highest amplifier bank. To switch on this amplifier bank, adown-threshold associated to the highest amplifier bank and an averagepower output of the power amplifier are assessed to determine whetherthe average power output corresponds in at least a predetermined way tothe down-threshold, and if so, the lowest amplifier bank is thenswitched off.

According to another embodiment, prior to switching off the lowestamplifier bank, a count timer to switch the highest amplifier bank offis started, and the down-threshold associated with the highest amplifierbank is assessed responsive to an expiration of the count timer. Anaverage power output of the power amplifier is then assessed in order todetermine whether the average power output corresponds in at least apredetermined way to the down-threshold, and if so, a total number ofamplifier banks that are switched on is assessed to provide a totalnumber of amplifier banks on. It is then determined whether this totalnumber of amplifier banks switched on corresponds in a predetermined wayto a predefined value, and if not, the lowest amplifier bank is switchedoff. Specifically, in one embodiment, an amplifier bank that has beenswitched on for a longest period of time is assessed to provide ahighest amplifier bank to be switched off when the total number ofamplifier banks switched on corresponds in the predetermined way to thepredefined value, or otherwise, an amplifier bank that has been switchedoff is assessed to provide a lowest amplifier to be switched on.According to an embodiment, responsive to an expiration of a rotationtimer, a lowest amplifier bank is assessed and switched on when thetotal number of amplifier banks on corresponds in the predetermined wayto the predefined value, followed by a highest amplifier bank beingassessed and switched off.

In one embodiment, it is determined whether there are any more banksfrom the plurality of amplifier banks that are switched off, and aprevious power output is set to the current power output. The assessmentof a next lowest amplifier bank is repeated when there are more banksthat are switched off. According to an embodiment, a determination ismade as to whether the current power output corresponds in apredetermined way to a maximum power output, and if so, the maximumpower output is set to the current power output, followed by a selectionof a loading profile based on this new maximum power output. Similarly,in another embodiment, a determination is made as to whether the currentpower output corresponds in a predetermined way to a minimum poweroutput, and if so, the minimum power output is set to the current poweroutput, followed again with a selection of a loading profile based onthis minimum power output.

Pursuant to various embodiments, another method is provided thatincludes an assessment of an amplifier bank that has been switched onfor a longest period of time to provide a highest amplifier bank, adown-threshold associated to the highest amplifier bank, and an averagepower output of the power amplifier. The assessments of these values areused to determine whether the average power output corresponds in apredetermined way to the down-threshold, and if so, the highestamplifier bank is switched off.

In one specific embodiment, prior to switching the lowest amplifier bankoff, a count timer is started to switch the highest amplifier bank off,and responsive to expiration of the count timer, the down-thresholdassociated to the highest amplifier bank is assessed. An average poweroutput of the power amplifier is assessed to determine whether itcorresponds in at least a predetermined way to the down-threshold, andif so, a total number of amplifier banks that are switched on isassessed to determine whether it corresponds in at least a predeterminedway to a predefined value. If, however, this total number of amplifierbanks does not correspond to the predefined value, the lowest amplifierbank is accordingly switched off. For an embodiment, a lowest amplifierbank is assessed when the total number corresponds in the predeterminedto the predefined value, followed by an assessment of a highestamplifier bank. Accordingly, the lowest amplifier bank and the highestamplifier bank are switched off and on, respectively. In one embodiment,a previous power output is set to the current power output, followed bya determination as to whether there are any more banks from theplurality of amplifier banks that are switched on, and if so, theassessment of the highest amplifier bank is repeated for a nextamplifier bank that is switched on.

Pursuant to various embodiments, an apparatus has also been providedthat includes a plurality of amplifier banks, a controller circuitcoupled to the amplifier banks that determines whether a current poweroutput of the power amplifier corresponds at least in a predeterminedway to an up-threshold, and a switch circuit coupled to the amplifierbanks and the controller circuit that switches at least one amplifierbank from the plurality of amplifier banks when the current power outputof the power amplifier corresponds at least in the predetermined way tothe up-threshold. According to one embodiment, the controller circuitfurther determines whether an average power output of the poweramplifier corresponds at least in a predetermined way to adown-threshold and the switch circuit switches off at least oneamplifier bank from the plurality of amplifier banks when the averagepower output of the power amplifier corresponds at least in thepredetermined way to the down-threshold. The controller circuit furtherassesses an amplifier bank from the plurality of amplifier banks thathas been switched on for a longest period of time to provide the atleast one amplifier bank to be switched off, according to oneembodiment. In another embodiment, the controller circuit assesses anamplifier bank from the plurality of amplifier banks that has beenswitched on for a longest period of time to provide the at least oneamplifier bank to be switched on.

Through these various teachings, a power management technique has beenprovided that, among other things, optimizes the power of the amplifierby dynamically matching traffic patterns and power out capability. As aresult, current drain and cost of operation of the power amplifier havebeen reduced. The various embodiments also provide an on-demand approachto the power amplifier that is more autonomous than the prior art.Another advantage is that legacy customers can benefit using the variousembodiments described, since they provide savings even on single carrierinstallations without multiple modules to switch the amplifier banks.Thus, as capacity increases in an operator's cell site, more and moreattention is being given to the cost of operations, which is one of themost important goals in any general communications system.

For example, using the various embodiments provided, the forward linkpower amplifiers can account for 50% to 70% of the total power usage inthe base station equipment. In a typical feed-forward amplifier scheme,the final stages can account for 60% to 80% of the total current draw.The on-demand architecture provided by various embodiments, in essence,allows the amplifier to turn off available power reserved for peak usageduring busy hours, which translates to more efficient use of power thatreduces the cost of operation. Moreover, the power management techniquealso properly rotates the amplifier bank to balance the wear and tear ofthe power amplifier to extend its service lifetime. Again, this is oneof numerous ways that these various teachings can reduce the cost ofoperation while maintaining efficient power usage.

Referring now to the drawings, and in particular to FIG. 1, for purposesof providing an illustrative but nonexhaustive example to facilitatethis description, a communications system is shown and indicatedgenerally at numeral reference 100. Those skilled in the art, however,will recognize and appreciate that the specifics of this illustrativeexample are not specifics of the invention itself and that the teachingsset forth herein are applicable in a variety of alternative settings.For example, since the teachings described are not platform dependent,they can be applied to various systems, such as, but not limited to,Code Division Multiple Access (CDMA) systems, Time Division MultipleAccess (TDMA) systems, Universal Mobile Telecommunications Systems(UMTSs), and General Packet Radio Service (GPRS) systems. In fact, anycommunication networks that transmit data between nodes through cellsites are contemplated and are within the scope of the invention.

Referring now to the exemplary communication network shown in FIG. 1, aplurality of mobile stations 102, 104, 106 (three shown) communicateswith multiple base stations 108, 110 (two shown). Specifically, as istypically well known in the art, the mobile stations 102, 104, 106communicate with one another using base stations 108, 110 that arelocated in their geographical area. Because every transmission via thebase stations 108, 110 requires power usage, efficient use of the powercan, at times, affect the quality of communications between the mobilestations 102, 104, 106. For example, portions of the amplifier banksshould be turned off and/or decreased during off-peak hours to conserveenergy. Conversely, during peak hours, power usage should be turned onand/or increased to accommodate the demands of the mobile stations. Theefficient usage of these amplifier banks of the power amplifier canaffect the quality of communications between the mobile stations, but,at the same time, increase the cost of operations if the power amplifieris unnecessarily switched while waiting for demands from the mobilestations.

To address some of these issues, on-demand power amplifiers 112, 114implemented with the various embodiments are included at each of thebase stations 108, 110, respectively. Of course, although FIG. 1specifically shows an implementation at the base stations 108, 110,other components, such as a radio access network controller (not shown),may also be used. Since there are multiple ways to implement thesevarious teachings described, the base stations 108, 110 will be used asone example. These other implementations are within the present scope ofthe various teachings, since they are readily appreciated by one skilledin the art. Moreover, since current cell phones have many similarfunctions to that of computer devices, a mobile station will be hereinused to refer to any device that requires a power control system, whichincludes, but is not limited to, cell phones, personal digitalassistants, and/or computers.

Turning now to FIG. 2, an apparatus according to one embodiment is shownand indicated generally at numeral reference 200. Specifically, afeed-forward power amplifier 200 has been shown as an example. Pleasenote, however, the various teachings described contemplateimplementation in other linear power amplifiers, such as a digitalpre-distorted power amplifier and a negative feedback power amplifier.In fact, other non-linear power amplifiers, such as frequency modulationclass C power amplifiers, are also contemplated. As such, it should bewell understood that the various embodiments described are not limitedto the specific exemplary feed-forward power amplifier apparatus 200,and other apparatus implementations are readily appreciated by a skilledartisan and are within the scope of the various embodiments. Moreover,“circuit” refers to one or more component devices such as, but notlimited to, those component devices referred to herein, processors,memory devices, application specific integrated circuits (ASICs), and/orfirmware, which are created to implement or adapted to implement(perhaps through the use of software) certain functionality, all withinthe scope of the various teachings described.

For this particular exemplary apparatus 200, a controller circuit 202 isincluded to control, among other things, a plurality of amplifier banks1 through N, designated as numeral references 204, 206, 208, and 210. Inparticular, as typically done in a feed-forward power amplifier, powerat an input side 212 goes to a main path 214 and an error path 216. Atthe main path 214, the power input 212 goes to a main low level gain 218that adds a prefixed level of power to the power input, depending uponthe system configuration of the communications system. The power input212 then continues to a main gain adjuster 220 and a main phase adjuster222 for a typical adjustment of the gain and phase value, which iscontrolled by the controller circuit 202. The power input 212 is thendivided by switch circuits 224, 226, 228, 230 to the multiple amplifierbanks 1 through N 204, 206, 208, 210. In this example, the controllercircuit 202 controls multiple thresholds that affects the gain and phaseadjustment and the division of the power input 212 into the multipleamplifier banks 1 through N 204, 206, 208, 210. Specifically, amongother things, the controller circuit 202 switches a current status ofeach of the multiple amplifier banks 1 through N 204, 206, 208, 210 toproduce a more efficient usage of the power amplifier by assessingmultiple considerations, such as current traffic and demands in thesystem. After the needed adjustments, a power output 232 based on addedoutputs of the multiple amplifier banks 1 through N 204, 206, 208, 210and a delay adjustment by a main delay element 234 that delays the feedof the power output for synchronization with the error path 216.

At the error path 216, the power input 212 is similarly forwarded to anerror delay element 236 that synchronizes the timing of the output feedwith the main path 214. After a predefined delay, the power input 212 isforwarded to an error low level gain 238 that amplifies the distortionof the power input, which is then forwarded to an error gain adjuster240 and an error phase adjuster 242 for adjusting a gain and phase valuecontrolled by the controller circuit 202. After these adjustments of thegain and phase value are made, the power input is output to a finallevel gain 244 that output an error output to be combined with the poweroutput 232. As shown, a general flow of the power input 212 and thepower output 232 has been described. Because the controller circuit 202provides multiple controls within the various routes of the generalflow, it can provide a more efficient power amplifier, since thecontroller circuit takes an on-demand approach having a more holisticview of the system and demands on the system. As a result, an apparatushas been provided that reduces the cost of operation by reducingunneeded power usage, while at the time maintaining efficient usage ofthe power to provide quality service to the mobile stations.

Turning now to FIG. 3, a flow chart of a power management processaccording to an embodiment is shown and indicated generally at numeralreference 300. Although the process shown is preferably implemented atthe base stations 108, 110, there may be other implementations of eachof the processes shown that are better suited for a radio access networkcontroller (not shown) and/or the mobile stations 102, 104, 106 in thecommunication system. These processes shown, thus, can be implementedfully or partially at any of the components within the system. Moreover,as one skilled in the art can readily appreciate, any of the processesshown can be altered in multiple ways to achieve the same functions andresults of the various teachings described. As a result, these processesshown are one exemplary embodiment of multiple variation embodimentsthat may not be specifically shown. Thus, the processes shown aredirected to the system, and each of them may be altered slightly toaccommodate any of the components in the communications system.Moreover, for the sake of brevity, “power output” is used as an example,but any monitored power, which includes but is not limited to input,output, or any other source of power, is contemplated. Thus, it shouldbe understood that power output used in the remaining description ofapplication includes any type of monitored power. These otherembodiments, however, are within the scope of the various teachingsdescribed.

The particular process 300 shown starts 302 with an initialization 304of a power threshold value and a counter value. For every predefined “x”milliseconds 306, a power output of a power amplifier having multiplebanks is assessed 308 to provide a current power output of the poweramplifier, which is compared to determine 310 whether it corresponds inat least a predetermined way (e.g., greater than in this example shown)to the power threshold. If not, the process 300 loops back and waits forevery x milliseconds 306 to reassess the power output of the poweramplifier. If, on the other hand, the current power output doescorrespond in at least the predetermined way (e.g., is greater than) tothe power threshold, the counter value is incremented 312 and anothercomparison is made. Specifically, the counter value, after beingincremented 312, is compared to determine 314 whether it corresponds inat least a predetermined way (e.g., greater than) to a counterthreshold. If not, the process 300 is again looped back to wait forevery x milliseconds 306. Otherwise, if the counter value is greaterthan the counter threshold, another switch subroutine 316 for switchingthe amplifier bank is executed, which is shown in FIG. 4. After thesubroutine 316 is processed, the counter value will be then reset andthe process loops back to wait for every x milliseconds 306.

Turning now to FIG. 4, a flow chart of a switch process 316, which isalso the switch subroutine from FIG. 3, is shown according to oneembodiment. The switch process 316 starts with detection 400 of at leastone amplifier bank that has been unchanged for the longest period oftime to provide at least one detected amplifier bank, which is switched402 to change a current status of the detected amplifier bank. Forexample, if the detected amplifier bank is switched on, the detectedamplifier bank is then switched off, and vice versa. Next, a totalnumber of amplifier banks of a predefined status is assessed 404 toprovide an assessed total value. In other words, the process 316 eitherassesses a total number of amplifier banks that may be currently on oroff in order to obtain the assessed total value, and using this value, acurrent state of the power amplifier is assessed 406. Thereafter, anadjust gain and phase value based on the current state of the poweramplifier is assessed 408 and used to adjust 410 the gain and phase ofthe power amplifier.

Once the gain and phase of the power amplifier has been adjusted 410, apredefined power threshold is assessed 412 based on the current stateand change 414 the power threshold of the power amplifier, and theprocess ends or returns 416 to FIG. 3. It should be noted, however, thatthese predefined power thresholds can be static thresholds stored in alist and/or can be dynamic thresholds that are adjusted with one or moreiterations. Moreover, the predefined power threshold can include asingle threshold for the power amplifier for each current state and/orfor an amplifier bank for each current state. As readily appreciated byone skilled in the art, there are countless ways to implement thepredefined thresholds for the power amplifier, and as such, thesevariations of the predefined power threshold, which may include one or aplurality of thresholds for one or more states of the power amplifier,are within the scope of the various teachings provided.

Referring now to FIG. 5, a flow chart of a power management processimplemented with static predefined threshold of the power amplifieraccording to an embodiment is shown and indicated generally at 500. Thepower management process 500, as shown, starts 502 with aninitialization 504 of an up-power threshold, a down-power threshold, anup-counter value, and a down-counter value. After numerous values havebeen initialized 504, for every x millisecond 506, a power output of thepower amplifier is assessed 508 to provide a current power output. Thiscurrent power output is compared to determine 510 whether it correspondsin at least a predetermined way (e.g., greater than in the embodiment)to the up-power threshold to check if the power amplifier should beincreased. If not, the current power value is compared to determine 512whether it is greater than the down-power threshold to check if thepower amplifier should be decreased, instead. This is specifically doneto determine whether the power amplifier should be changed or simplylooped back to wait for every x millisecond 506 if no action is neededto adjust the power amplifier.

If the current power output does correspond in at least thepredetermined way to (e.g., is greater than) the up-power threshold, theup-counter value is incremented 514 and the down-counter is reset 516 toprepare for power adjustment of the amplifier. The up-counter value iscompared with an up-count threshold to determine 518 whether theycorrespond to one another in at least a predetermined way, such aswhether the up-count threshold is greater than the up-count threshold.If not, no change in the power usage of the power amplifier will beeffectuated, and the process 500 loops back to wait for every xmillisecond to run another iteration. If, on the other hand, theup-counter value is greater than the up-count threshold, a subroutine520 assessment to switch on an amplifier bank is triggered, which isshown in FIG. 6. After this subroutine 520 has been processed, theup-counter is reset 522 again and the process 500 loops back to wait forevery x millisecond 506 to rerun the process from that point.

If the power amplifier should be decreased, meaning that the currentpower value is not greater than the down-power threshold 512, thedown-counter value is incremented 524 and the up-counter is reset 526 toagain prepare the power amplifier for an adjustment of a decrease inpower output. After this increment of the down counter value, it iscompared to determine 528 whether it corresponds in a predetermined wayto (e.g., greater than) a down-counter threshold. If not, the process500 does not prepare to change the power usage of the power amplifier,and instead loops back and waits to rerun the iteration again after xmilliseconds 506. If, however, the down-counter value corresponds in thepredetermined way to (e.g., is greater than) the down-counter threshold,a subroutine 530 assessment to switch off an amplifier bank shown inFIG. 7 is triggered. After this subroutine 530 has been processed, theup-counter is similarly reset 532 again and the process 500 loops backto wait for every x milliseconds 506 to rerun the process from thatpoint.

Turning now to FIG. 6, a flow chart of a switch-on process, according toan embodiment, from FIG. 5 is shown. The switch-on process 520 starts bymaking sure that not all amplifier banks are already on. Specifically,the process 520 determines 600 whether all amplifier banks in the poweramplifier are already switched on, and if so, the process 520 ends andreturns 602 to FIG. 5. If, however, not all the amplifier banks areswitched on, which means that at least one amplifier bank can beswitched on to increase the power, it is next determined 604 whether anerror amplifier has been switched on. If not, the error amplifier isswitched 606 on and the switch-on process ends and returns 602 to FIG.5. The error amplifier, as is well known in the art, should be switchedon to accommodate any distortion that must to be amplified. If, on theother hand, the error amplifier is already switched on, at least oneamplifier bank that has been off for a longest period of time isassessed 608 to provide at least one selected amplifier bank to beswitched on 610, specifically the transistor circuit and the directcurrent circuit of the selected amplifier bank is switched on 612, 614.

After the selected amplifier bank is switched on, a total number ofamplifier banks that have been switched on is assessed 616 to provide anassessed on-total value, which is used to assess 618 a current state ofthe power amplifier. An adjust gain and phase value is then assessed 620based, at least in part, on this current state and a gain and phasevalue of the power amplifier is, in turn, adjusted 622 based, at leastin part, on this adjust gain and phase value. A predefined up-power anddown-power threshold is also assessed 624 based, at least in part, onthe current state, and the up-power and down-power threshold is changedbased, at least in part, on these predefined threshold values. Theprocess 520 ends and returns to FIG. 5 at this point.

Turning now to FIG. 7, a flow chart of a switch-off process from FIG. 5is shown according to an embodiment. The switch-off process 530 startswith an assessment 700 of a total number of amplifier banks that areswitched on to provide an on-total value, which is compared to determine702 whether it corresponds in a predetermined way to (e.g., greaterthan) a predefined number. This comparison to the predefined number isincluded to make sure that the power amplifier is never completely off.In other words, to ensure the power amplifier is up and ready for anypower adjustment, at least one amplifier bank should be switched on tokeep the power amplifier active and ready, and this predefined numberdepends upon the power demands of the communications system. Referringback to FIG. 7, if the on-total value is not greater than the predefinednumber, it is next determined 704 whether an error amplifier has beenswitched on. If the error amplifier is not switched on, meaning it isswitched off, the process 530 ends and returns 706 to FIG. 5. If, on theother hand, the error amplifier is switched on, the process 530 switches708 the error amplifier off and loops to end 706 the process and returnto FIG. 5.

If, however, the on-total value is greater than the predefined number,at least one amplifier bank that has been switched on for a longestperiod of time is assessed 710 and switched 712 off. Specifically, thetransistor circuit and the direct current circuit of the amplifier bankare switched off 714, 716. After at least one amplifier has beenswitched 712 off, a total number of amplifier banks that are off isassessed 718 to provide an off-total value, which is used to assess 720a current state of the power amplifier. An adjust gain and phase valueis again assessed 722 based, at least in part, on the current state, anda gain and phase value of the power amplifier is accordingly adjusted724 based on this adjust gain and phase value. Moreover, using thecurrent state of the power amplifier, a predefined up-power thresholdand a down-power threshold are assessed 726 based, at least in part, onthe current state. The up-power and down-power thresholds areaccordingly changed 728 based on these predefined assessed thresholds,which brings the process 530 to an end 706 to return to FIG. 5.

Referring now to FIG. 8, a flow chart of a power management processimplemented with dynamic predefined thresholds of the amplifier banksaccording to an embodiment is shown and indicated generally at numeralreference 800. The power management process 800 starts 802 with aninitialization 804 of a rotation timer and a setup timer, followed by anassessment 806 of a power output of the power amplifier to provide acurrent power output. A previous power output is set 808 to the currentpower output, and a maximum power output and a minimum power output isalso set 810, 812 to this current power output. A predefined profile isalso loaded 814, which finalizes the initialization of the process 800.For every x milliseconds 816, another subroutine starts with anassessment of the previous power output 818 and the current power output820 of the power amplifier. A min/max output power update subroutineprocess 822 is next executed to update the maximum power output and theminimum power output. The min/max output power update subroutine process822 will be described later in FIG. 9. After the minimum and maximumpower output has been updated via the process 822, it is determined 824whether a previous power output corresponds in at least a predeterminedway to (e.g., is greater than) the current power output, and if so, theprocess 800 will decrease the power outputted by power amplifier. If,otherwise, the previous power output does not correspond to (e.g., isnot greater than) the current power output, the process 800 increasesthe power outputted by power amplifier.

Turning first to the subroutine to increase the power amplifier, anamplifier bank that has been switched off the longest period of time isassessed 826 to provide a lowest amplifier bank. An up-thresholdassociated with the lowest amplifier bank is assessed 828 to determine830 whether the current power output corresponds in at least apredetermined way to (and specifically whether it is greater than inthis embodiment shown) the up-threshold. If, in fact, the current poweroutput is greater than the up-threshold, the lowest amplifier isswitched 832 on to output more power, or otherwise, the subroutine endswithout switching on the lowest amplifier bank. The process 800 nextdetermines whether there any more amplifier banks that may be off, andif so, loops back to rerun the subroutine from the assessment 826 of anext lowest amplifier bank until all the amplifier banks that are offhave been accounted for. If, on the other hand, there are not any moreamplifier banks that are switched off, the process 800 continues andsets 836 the previous power output to the current power output to rerunthe iteration every x milliseconds 816.

Turning next to the subroutine for decreasing the power of the poweramplifier, an amplifier bank that has been switched on the longest isassessed 838 to provide a highest amplifier bank. In this case, adown-threshold associated with the highest amplifier bank is assessed840, followed by an average power output of the power amplifier beingassessed 842. It is then determined 844 whether the average power outputcorresponds in at least a predetermined way to (e.g., less than in thisembodiment shown) the down-threshold, and if so, the count timerassociated with this highest amplifier bank is started 846 to count downa time period to switch off the highest amplifier bank. This part of thesubroutine is again finished for a particular amplifier bank, and theprocess 800 continues to determine 848 whether there are any moreamplifier banks that may be switched on so that they can be switched offto reduce the power of the power amplifier. If there are, in fact, moreamplifier banks that may be switched off, the process 800 continues toloop back from the assessment 838 of a next highest amplifier bank. Thispart of the process 800 is executed until the amplifier banks that areswitched off have been accounted for. Again, the process 800 continuesand sets 836 the previous power output to the current power output towait for every x milliseconds 816 to rerun the iteration.

Referring now to FIG. 9, a flow chart of a min/max output power updateprocess 822 from FIG. 8 is shown according to one embodiment. Theprocess 822 starts with a comparison to determine 900 whether thecurrent output corresponds in at least a predetermined way to (in thiscase whether it is greater than) the maximum power output, and if so,the maximum power output is set 902 to the current power output and aloading profile that is based on the maximum power output is loaded 904.If, however, the current power output is not greater than the maximumpower output 900 and/or after the new loading profile has been loaded904, the current power is then compared to determine 906 whether itcorresponds in at least a predetermined way to (e.g., less than in thisembodiment shown) the minimum power output. Again, if this is the case,the minimum power output is updated by being set 908 to the currentpower output, and accordingly, a loading profile based on this newminimum power output is loaded 910. Either when the current power outputis not less than the minimum power output 906 and/or after the newloading profile is loaded based on an updated minimum output, theprocess 822 ends 910 and returns to FIG. 8.

Turning now to FIG. 10, a flow chart of a setup timer expiration processaccording to an embodiment is shown and indicated generally at numeralreference 1000. This process 1000 is triggered 1002 with an expirationof the setup timer. A power output of the power amplifier is assessed1004 to provide a current power output. The maximum power output and theminimum power output are set 1006, 1008 to this current power output,followed by the setup timer being reset 1010, which ends 1012 theprocess 1000.

Referring now to FIG. 11, a flow chart of a count timer expirationprocess according to an embodiment is shown and indicated generally at2000. Recall from FIG. 8 that a count timer is started before aparticular amplifier bank can be switched off. According to thisembodiment, a multiple count timer associated with different amplifierbanks may be started to wait for the timing to be switched off. Thisprocess 2000 describes an expiration of a count timer 2002 that isassociated with a particular amplifier bank waiting to be switched off.At which time, a down-threshold associated with this particularamplifier bank and an average power output of the power amplifier areassessed 2004, 2006. Using these assessed values, a comparison is doneto determine 2008 whether the average power output corresponds in atleast a predetermined way to (e.g., less than in this embodiment shown)the down-threshold, and if not, the process 2000 ends 2020 until a nextcount timer expires. If, however, the average power output is less thanthe down-threshold, a total number of amplifier banks that are switchedon is assessed 2012 to provide an on-total value, which is used todetermine 2014 whether the on-total value corresponds in at least apredetermined way to (and specifically whether it is equal to in thisembodiment shown) a predefined value. If not, the amplifier bankassociated with the expired count timer is switched 2016 off and theprocess 2000 ends 2020 at this point. If, on the other hand, theon-total value is equal to the predefined value, a rotate banks process2018 shown in FIG. 13 is triggered, which brings the process 2000 to anend.

Turning now to FIG. 12, aside from the count timer expiration process,the rotate banks process 2018 can also be triggered with an expirationof the rotation timer, which will be referred to as the rotation timerexpiration process and indicated generally at numeral reference 3000. Asstated, this process 3000 is triggered with the expiration 3002 of therotation timer. The rotate banks process 2018 shown in FIG. 13 is theninitiated in response, and the rotation timer is accordingly reset 3004after the rotate banks process has been processed, which brings theprocess 3000 to an end 3006. Note that the rotate banks process 2018 canbe executed from multiple routes.

Referring now to the rotate banks process 2018 shown in FIG. 13, anamplifier bank that has been switched off for a longest period of timeis assessed 4000 to provide a lowest amplifier bank. A highest amplifierbank is also provided through another assessment 4002 of an amplifierbank that has been switched on for a longest period of time. To rotatethe amplifier banks in order to increase their lifetime expectancy, thelowest amplifier bank is switched 4004 on and the highest amplifier bankis switched 4006 off, and the process 2018 ends 4008 at this point.

With these various teachings shown, a power management technique hasbeen provided that, among other things, optimizes the power of theamplifier by dynamically matching traffic patterns and power outcapability. This optimization, as a result, reduces the current drainand the cost of operation of power amplifier. An on-demand approach ofthe power amplifier has been provided that is more autonomous. Thevarious embodiments can be more easily implemented with legacy customersthat can take advantage of savings of costs of operation even for singlecarrier installations without multiple modules for switching theamplifier banks. Thus, as capacity increases in an operator's cell site,more and more attention is being given to cost of operations, which isone of the most important goals in any general communications system.

For example, using the various embodiments provided, the forward linkpower amplifiers can account for 50% to 70% of the total power usage inthe base station equipment. In a typical feed-forward amplifier scheme,the final stages can account for 60% to 80% of the total current draw.The on-demand architecture provided by various embodiments, in essence,allows the amplifier to turn off available power reserved for peak usageduring, for example, busy hours, which translates to more efficient useof power that reduces the cost of operation. Moreover, the powermanagement technique also properly rotates the amplifier bank to balancethe wear and tear of the power amplifier to extend its service lifetime.Again, this is one of numerous ways that the various teachings canreduce the cost of operation, while maintaining efficient power usage.

Those skilled in the art will recognize that a wide variety ofmodifications, alterations, and combinations can be made with respect tothe above described embodiments without departing from the spirit andscope of the invention, and that such modifications, alterations, andcombinations are to be viewed as being within the ambit of the inventiveconcept.

1. A method comprising: assessing an amplifier bank from a plurality ofamplifier banks in a power amplifier that has been switched off for alongest period of time to provide a lowest amplifier bank; assessing anup-threshold associated to the lowest amplifier bank; assessing acurrent power output of the power amplifier; determining whether thecurrent power output corresponds at least in a predetermined way to theup-threshold; switching the lowest amplifier bank on when the currentpower output corresponds at least in the predetermined way to theup-threshold.
 2. The method according to claim 1 further comprising,prior to assessing the amplifier bank from the plurality of amplifierbanks in the power amplifier that has been switched off for the longestperiod of time to provide the lowest amplifier bank: assessing a currentpower output of the power amplifier; setting a previous power output tothe current power output; waiting for a predefined period of time torepeat the method.
 3. The method according to claim 1 furthercomprising, prior to assessing the amplifier bank from the plurality ofamplifier banks in the power amplifier that has been switched off forthe longest period of time to provide the lowest amplifier bank:assessing a previous power output of the power amplifier; assessing acurrent power output of the power amplifier; determining whether theprevious power output corresponds at least in a predetermined way to thecurrent power output; assessing an amplifier bank from the plurality ofamplifier banks in the power amplifier that has been switched on for alongest period of time to provide a highest amplifier bank when theprevious power output does not correspond at least in the predeterminedway to the current power output.
 4. The method according to claim 3,wherein assessing the amplifier bank from the plurality of amplifierbanks in the power amplifier that has been switched on for the longestperiod of time to provide the highest amplifier bank further comprises:assessing a down-threshold associated to the highest amplifier bank;assessing an average power output of the power amplifier; determiningwhether the average power output corresponds in at least a predeterminedway to the down-threshold; switching the highest amplifier bank off whenthe average power output corresponds in the predetermined way to thedown-threshold.
 5. The method according to claim 4 further comprising,prior to switching the lowest amplifier bank off: starting a count timerto switch the highest amplifier bank off; assessing, responsive to anexpiration of the count timer, the down-threshold associated to thehighest amplifier bank; assessing an average power output of the poweramplifier; determining whether the average power output corresponds inat least a predetermined way to the down-threshold; assessing a totalnumber of amplifier banks that are switched on to provide a total numberof amplifier banks on when the average power output corresponds in atleast the predetermined way to the down-threshold; determining whetherthe total number of amplifier banks on corresponds in a predeterminedway to a predefined value; switching the highest amplifier bank off whenthe total number of amplifier banks on does not correspond in thepredetermined way to the predefined value.
 6. The method according toclaim 5 further comprising: assessing an amplifier bank that has beenswitched off for a longest period of time to provide a lowest amplifierbank when the total number of amplifier banks on corresponds in thepredetermined way to the predefined value; assessing an amplifier bankthat has been switched on for a longest period of time to provide ahighest amplifier bank; switching the lowest amplifier bank on;switching the highest amplifier bank off.
 7. The method according toclaim 5 further comprising: assessing, responsive to an expiration of arotation timer, an amplifier bank from the plurality of amplifier banksthat has been switched off for a longest period of time to provide alowest amplifier bank when the total number of amplifier banks oncorresponds in the predetermined way to the predefined value; assessingan amplifier bank that has switched on for a longest period of time toprovide a highest amplifier bank; switching the lowest amplifier bankon; switching the highest amplifier bank off.
 8. The method according toclaim 1 further comprising: determining whether there are any more banksfrom the plurality of amplifier banks that are switched off; setting aprevious power output to the current power output; repeating assessingan amplifier bank from the plurality of amplifier banks in the poweramplifier that has been switched off for a longest period of time toprovide a lowest amplifier bank when there are more banks from theplurality of amplifier banks that are switched off.
 9. The methodaccording to claim 1 further comprising, prior to determining whetherthe current power output corresponds at least in the predetermined wayto the up-threshold: determining whether the current power outputcorresponds in a predetermined way to a maximum power output; settingthe maximum power output to the current power output when the currentpower output corresponds in the predetermined way to the maximum poweroutput; selecting a loading profile based, at least in part, on themaximum power output.
 10. The method according to claim 1 furthercomprising, prior to determining whether the current power outputcorresponds at least in the predetermined way to the up-threshold:determining whether the current power output corresponds in apredetermined way to a minimum power output; setting the minimum poweroutput to the current power output when the current power outputcorresponds at least in the predetermined way to the minimum poweroutput; selecting a loading profile based, at least in part, on theminimum power output.
 11. The method according to claim 1 furthercomprising: assessing, responsive to an expiration of a setup timer, acurrent minimum power output of the power amplifier; setting a maximumpower output to the current power output; setting a minimum power outputto the current power output; resetting the setup timer.
 12. A methodcomprising: assessing an amplifier bank from a plurality of amplifierbanks in a power amplifier that has been switched on for a longestperiod of time to provide a highest amplifier bank; assessing adown-threshold associated to the highest amplifier bank; assessing anaverage power output of the power amplifier; determining whether theaverage power output corresponds in a predetermined way to thedown-threshold; switching the highest amplifier bank off when theaverage power output corresponds in the predetermined way to thedown-threshold.
 13. The method according to claim 12 further comprising,prior to switching the lowest amplifier bank off: starting a count timerto switch the highest amplifier bank off; assessing, responsive to anexpiration of the count timer, the down-threshold associated to thehighest amplifier bank; assessing an average power output of the poweramplifier; determining whether the average power output corresponds inat least a predetermined way to the down-threshold; assessing a totalnumber of amplifier banks that are switched on to provide a total numberof amplifier banks on when the average power output corresponds in atleast the predefined way to the down-threshold; determining whether thetotal number of amplifier banks on corresponds in a predetermined way toa predefined value; switching the highest amplifier bank off when thetotal number of amplifier banks on does not correspond in thepredetermined way to the predefined value.
 14. The method according toclaim 13 further comprising: assessing an amplifier bank that has beenswitched off for a longest period of time to provide a lowest amplifierbank when the total number of amplifier banks on corresponds in thepredetermined way to the predefined value; assessing an amplifier bankthat has switched on for a longest period of time to provide a highestamplifier bank; switching the lowest amplifier bank on; switching thehighest amplifier bank off.
 15. The method according to claim 12 furthercomprising: determining whether there are any more banks from theplurality of amplifier banks that are switched on; setting a previouspower output to the current power output; repeating assessing anamplifier bank from the plurality of amplifier banks in the poweramplifier that has been switched on for a longest period of time toprovide a highest amplifier bank when there are more banks from theplurality of amplifier banks that are switched on.
 16. An apparatuscomprising: a plurality of amplifier banks of a power amplifier; acontroller circuit coupled to the plurality of amplifier banks, whereinthe controller circuit determines whether a current power output of thepower amplifier corresponds at least in a predetermined way to anup-threshold; a switch circuit coupled to the plurality of amplifierbanks and to the controller circuit, wherein the switch circuit switcheson at least one amplifier bank from the plurality of amplifier bankswhen the current power output of the power amplifier corresponds atleast in the predetermined way to the up-threshold.
 17. The apparatusaccording to claim 16, wherein the controller circuit further determineswhether an average power output of the power amplifier corresponds atleast in a predetermined way to a down-threshold and the switch circuitfurther switches off at least one amplifier bank from the plurality ofamplifier banks when the average power output of the power amplifiercorresponds at least in the predetermined way to the down-threshold. 18.The apparatus according to claim 17, wherein the controller circuitfurther assesses an amplifier bank from the plurality of amplifier banksthat has been switched on for a longest period of time to provide the atleast one amplifier bank to be switched off.
 19. The apparatus accordingto claim 16, wherein the controller circuit further assesses anamplifier bank from the plurality of amplifier banks that has beenswitched off for a longest period of time to provide the at least oneamplifier bank to be switched on.